<!doctype html>
<html ng-app>
    <head>
        <meta charset="utf-8">
        <script src="http://apps.bdimg.com/libs/angular.js/1.3.0-beta.8/angular.min.js"></script>
    </head>
    <body>
        <div ng-controller="InvoiceCntl">
            <b>Invoice:</b>
            <br>
            <br>
            <table>
                <tr><td>Quantity</td><td>Cost</td></tr>
                <tr>
                    <td><input type="integer" min="0" ng-model="qty" required ></td>
                    <td><input type="number" ng-model="cost" required ></td>
                </tr>
            </table>
            <hr>
            <b>Total:</b> {{qty * cost | currency}}
        </div>
        <script type="text/javascript">
	        function InvoiceCntl($scope) {
				$scope.qty = 1;
				$scope.cost = 19.95;
			}
        </script>
    </body>
</html>